Magnetic connector having a unitary housing

ABSTRACT

Power cables that include plug housings having an improved appearance as well as employ a halogen-free cable while providing adequate fire resistance. One example provides a power cable having cable plug with a substantially unitary body. Another example provides a power cable that is formed using halogen-free materials. To provide adequate fire protection, a strain relief formed using multiple materials is used.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/582,308, filed October 20, 2009, now U.S. Pat. No. 8,535,088,entitled “MAGNETIC CONNECTOR HAVING A UNITARY HOUSING”, which isincorporated by reference.

BACKGROUND

Portable electronic devices have become increasingly popular the pastseveral years. Laptop and netbook computers, cell phones, portable mediadevices, and the like have become ubiquitous, and soon notebook andtablet computing devices will follow.

These devices include batteries that provide power. Unfortunately, thesebatteries need recharging. This recharging is often performed using apower cable having a connector insert or cable plug that mates with aconnector receptacle on the portable device. Power can be supplied by apower transformer that receives power from a wall outlet, vehiclecharging outlet, or other source. The power transformer converts thepower from the outlet to a power level that can be used to charge thebattery in a portable device. In some circumstances, these power cablesmay also convey signals between the portable device and a secondelectronic device.

The connector insert or cable plug may include circuitry inside of aplug housing. The plug housing typically is formed using several piecesthat fit together around the circuitry. This patchwork of pieces used toform a plug housing can result in a housing having a less than optimalappearance.

The cable can include a conductor surrounded by an insulating layer.This conductor can be used to convey a power supply, such as a positivepower supply voltage. The insulating layer can be further surrounded bya metallic braid layer that is used to convey ground. The braiding maybe covered with a polyvinyl chloride coating. This coating provides afire resistance to protect the electronic device in the event that thepower transformer overheats or catches on fire. However, for variousreasons, it is environmentally undesirable to use materials such aspolyvinyl chloride. Unfortunately, halogen-free cables do not provideadequate fire resistance.

Thus, what is needed are improved power cables that have plug housingsthat provide an improved appearance as well as employ a halogen-freecable while providing adequate fire resistance.

SUMMARY

Accordingly, embodiments of the present invention provide power cablesthat include cable plug housings having an improved appearance as wellas employing a halogen-free cable while providing adequate fireresistance.

A specific embodiment of the present invention provides a power cablehaving a cable plug or connector insert with a unitary (made from asingle piece) or substantially unitary body. This body provides animproved appearance, greater strength and durability, and is simple tomanufacture at a reduced cost. The cable plug can receive a power cableand may provide contacts for power transmission. The housing may besubstantially unitary, that is, it may be made predominantly using asingle piece of material. The single piece of material may be formedusing metal, such as aluminum. The single piece of material mayalternately be formed using plastic, ceramic, or other material. Thesingle piece may be approximately cylindrical, or it may have othershapes, such as oval, square, or other shapes or combinations of shapes.

The contacts or terminals may extend from the cable plug housing and maybe protected by a protrusion that mates with a connector receptacle onan electronic device. In various embodiments of the present invention,the protrusion is a magnetic element that is attracted to a secondmagnetic element in the connector receptacle. These magnetic elementsmay be magnets, attraction plates, or other types of magnetic elements,such as electromagnets. The attraction plates may be formed using aferromagnetic material. In a specific embodiment of the presentinvention, the connector insert protrusion can include an attractionplate that is attracted to a magnetic element located in the connectorreceptacle.

Another specific embodiment of the present invention provides a powercable that is formed using halogen-free materials. To provide adequatefire protection, a strain relief formed using multiple materials isused. This strain relief can provide an interface between the cable anda housing, for example, a housing enclosing a power transformer. Thestrain relief can include a first, interior portion formed using arigid, fire-resistant material. The fire-resistant material may be apolycarbonate, polycarbonate ABS (PC/ABS) blend, or other appropriatematerial. The strain relief may include a second, exterior portionformed using a flexible material. This material may be a thermoplasticelastomer (TPE), fluorinated ethylene propylene (FEP), or otherappropriate material.

Various embodiments of the present invention may incorporate one or moreof these and the other features described herein. A better understandingof the nature and advantages of the present invention may be gained byreference to the following detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a power cable assembly according to an embodiment ofthe present invention;

FIG. 2 illustrates a cable plug according to an embodiment of thepresent invention;

FIG. 3 illustrates components that may be used to construct a cable plugaccording to an embodiment of the present invention;

FIG. 4 illustrates a side view of a portion of a cable plug according toan embodiment of the present invention;

FIG. 5 illustrates portions of a strain relief according to anembodiment of the present invention; and

FIG. 6 illustrates a strain relief according to an embodiment of thepresent invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 illustrates a power cable assembly 100 according to an embodimentof the present invention. This figure, as with the other includedfigures, is shown for illustrative purposes and does not limit eitherthe possible embodiments of the present invention or the claims.

Power cable assembly 100 may be used for providing power to anelectronic device, such as a laptop, netbook, notebook, tablet computer,media player, portable media player, cell phone, or other type ofelectronic device. Cable assembly 100 may also be used to convey signalsbetween such devices. Cable assembly 100 may include cable plug 105 andstrain relief 140 connected together via cable 150.

Cable plug 105 may mate with a compatible connector receptacle (notshown.) Cable plug 105 may include housing 110, attraction plate 125,and strain relief 115. Housing 110 may be unitary or substantiallyunitary. This unitary construction can provide a connector plug 105having an improved appearance, increased strength, and reducedmanufacturing costs. Housing 110 may be formed using metal, such asaluminum, plastic, ceramic, or other material.

Attraction plate 125 may be formed around contacts 130. Attraction plate125 may have two axes of symmetry, allowing cable plug 105 to mate witha compatible connector receptacle in at least two orientations.Attraction plate 125 may be formed of metal, plastic, ceramic, or othermaterial. For example, the attraction plate may be made using aferromagnetic material.

A dust cover (not shown) may cover the sides of attraction plate 125 andthe contacts 130. The dust cover may be formed using metal, plastic,ceramic, or other material. For example, it may be formed of atransparent plastic. The dust cover may form a seal, reducing oreliminating the amount of dust particles entering housing 110 when cableassembly 100 is transported. To prevent the loss of the dust cover, thedust cover may be attached to the cable assembly 100 by a tie, cord,wire, or other fastener.

Contacts 130, which may also be referred to as signal terminals or pins,may include contacts for signal and power supplies, such as power andground. Cable plug 105 can include five such contacts, though in otherembodiments of the present invention, other numbers of contacts may beincluded. For example, three contacts may be included. Also in otherembodiments of the present invention, one or more contact forfiber-optic cables may be included. The center pin may be a detect pinthat detects that cable plug 105 has mated with a compatible connecterreceptacle. Two ground pins may be located on each side of the detectpin. Two power supply pins may be located on each side of the detect pinbetween the detect pin and the ground pins. Alternately, the ground pinsmay be located between the power supply pins and the detect pin. Thecontacts may be retractable, that is, they may be biased, for example bya spring.

Cable plug 105 can include a strain relief 115. Strain relief 115 may beformed of a flexible material. For example, it may be made of ahalogen-free material. In a specific embodiment of the presentinvention, it can be formed using a thermoplastic elastomer, fluorinatedethylene propylene, or other appropriate material.

Strain relief 140 and cabling 152 can form a pigtail that may be used toconnect power cable assembly 100 to a power supply. For example, thepigtail may be housed in an enclosure that includes a power transformeror other circuitry. For example, the enclosure may have power prongs orother connections to receive power from a wall socket, vehicle outlet,or other power supply. Circuitry internal to the housing can convert thereceived power supply to a power level appropriate for the electronicdevice to be charged. Cabling 152 may connect to this power conversioncircuitry, such as a power transformer that converts AC power to DCpower. Alternately, cabling 152 may connect to power conversioncircuitry that converts a first DC power supply to a second DC powersupply. The housing may also include wired or wireless datacommunications and other electronic circuits. Cabling 152 may includefurther connections for these circuits.

Strain relief 140 can include an interior portion 145 and exteriorportion 147. Interior portion 145 may be inside the housing (not shown)that also includes the power transformers or other electricalcomponents. Exterior portion 147 may be located outside of this housing.Inside portion 145 may be formed using a hard plastic, such as apolycarbonate, polycarbonate ABS blend or other appropriate material,for fire protection. Exterior portion 147 may be formed using a moreflexible material, such as a thermoplastic elastomer, fluorinatedethylene propylene, or other appropriate material.

Strain relief 140 may provide an interface between cable 150 and thehousing. Strain relief 140 can allow cable 150 to be flexed or movedrelative to the housing, such that cable 150 does not wear excessively.Strain relief 115 can similarly protect cable 150 at its interface withcable plug 105.

Cable 150 may be formed with an inside conductor surrounded by ametallic braiding. The inside conductor may be used to convey power,while the braiding may be used to convey ground. Isolation layers may beincluded between the inside conductor and the braiding, and outside ofthe cable around the braiding. Cable 150 may be made of a halogen-freematerial. For example, it may be formed using a thermoplastic elastomer,fluorinated ethylene propylene, or other appropriate material. Cable 150may include additional conductors for conveying signals, for example,those provided by wired or wireless data communications and otherelectronic circuits located in the housing that includes the powertransformer or conversion circuitry. Cable 150 may also include one ormore fiber-optic cables.

Again, it is desirable to provide a cable plug 105 having an attractiveappearance, and that is durable and easy to manufacture. Accordingly,embodiments of the present invention provide a cable plug 105 having aunitary or substantially unitary housing. An example is shown in thefollowing figure.

FIG. 2 illustrates a cable plug 205 according to an embodiment of thepresent invention. Cable plug 205 may also be referred to as a connectorinsert. Cable plug 205 can include housing 210, attraction plate 225,contacts 230, and strain relief 215. Cable 250 can attach to cable plug205. Attraction plate 225 can protect contacts 230 and can bemagnetically attracted to magnets located in a compatible connectorreceptacle. A dust cover (not shown) may be employed to preventparticulate matter from entering housing 210 when the cable assembly istransported. Housing 210 may also include a light-emitting diode (LED)exit 212. Exit 212 may allow light from an LED inside housing 210 toescape. In a specific embodiment of the present invention, a lit LED mayindicate that an electrical connection has been made between cable plug205 and a compatible receptacle (not shown.)

Housing 210 may be unitary, though in other embodiments of the presentinvention it may be substantially unitary. In this example, housing 210is cylindrical, though in other embodiments of the present inventionhousing 210 may have other shapes. Housing 210 may provide an attractiveappearance, and may be durable and easy to manufacture. Housing 210 maybe metallic, plastic, ceramic, or formed using another material. In aspecific embodiment of the present invention, housing 210 is made ofaluminum.

Attraction plate 225 may have two axes of symmetry, allowing cable plug205 to mate with a compatible connector receptacle in at least twoorientations. The attraction plate may be metallic, such that it isattracted to magnets inside the connector receptacle. These magnets mayhave opposing polarities, such that magnetic field lines that originatein one magnet travel through attraction plate 225 and terminate in asecond magnet. Attraction plate 225 can, for example, be formed using aferromagnetic material. In other embodiments of the present invention,attraction plate 225 may be formed using one or more magnets, such asrare-earth magnets or electromagnets.

A dust cover (not shown), may be arranged to cover attraction plate 225and contacts 230. The dust cover may be formed using metal, plastic,ceramic, or other material. For example, the dust cover may be made of atransparent plastic. This transparent plastic may be colored to providea pleasing appearance.

Contacts 230 may be pogo pins or other types of contacts. Contacts 230may include a center contact. The center contact may be a detect pin.Alternately, it may be a fiber-optic connection, signal pin, or othertype of contact, signal terminal, or pin. The two contacts 230 on eachside of the center pin may convey a positive power supply, though theymay alternately convey ground. The two outside contacts 230 may conveyground, though they may alternately convey a positive power supply.Contacts 230 are typically metallic, such that they are conductive.Contacts 230 may be formed using brass, copper, or other metals.

Strain relief 215 can protect cable 250 from excessive wear that couldotherwise result at the interface with housing 210 when cable 250 ismoved or flexed relative to housing 210. Strain relief 215 may be formedusing a flexible material, such as a thermoplastic elastomer,fluorinated ethylene propylene, or other appropriate material.

Again, it is desirable that cable plug 205 be robust and simple tomanufacture. An example of the components that may be used to constructcable plug 205 according to an embodiment of the present invention isshown in the following figure.

FIG. 3 illustrates components that may be used to construct a cable plug305 according to an embodiment of the present invention. Cable plug 305may include housing 310, strain relief 315, cable 350, crimping ring355, assembly 340, contacts 330 and 332, front plate 335, attractionplate 325, dust cover 320, circuit board 360, LEDs 365, light pipes 370,and light insulators 380.

Housing 310 may include an LED exit 312. LED exit 312 may be an actualhole, or it may be a number of small perforations. In a specificembodiment of the present invention, these perforations may be on theorder of 0.03 mm in size. At this size, the individual perforations maynot be not visible unless light is emitting through them. Again, housing310 may be metal, for example aluminum, plastic, ceramic, or it may bemade of another material.

Strain relief 315 may receive cable 350. Strain relief 315 can beflexible and may prevent housing 310 from wearing cable 350 as cable 350moves relative to housing 310 during use. Strain relief 315 may be madeof a flexible material, such as a thermoplastic elastomer, fluorinatedethylene propylene, or other flexible material.

Cable 350 passes through strain relief 315. Cable 350 may include acenter conductor for providing a positive power supply. Cable 350 mayinclude other conductors, fiber-optic cables, or other signal or powerconduits. The center conductor may be insulated and surrounded by ametallic braiding. The metallic braiding may be used to covey ground.The metallic braiding may be further insulated. Various embodiments ofthe present invention use a halogen-free coating or jacket, such as acoating formed using a thermoplastic elastomer, or other appropriatematerial.

Crimping ring 355 can crimp cable 350. Crimping ring 355 may bemetallic, plastic, or formed using other materials. Crimping ring 355may prevent cable 350 from splitting due to stresses that may resultwith usage. Crimping ring 355 may also provide strain relief. In variousembodiments of the present invention, crimping ring 355 may connectmechanically and (or) electrically to any or all of the metal braidingof cable 350, assembly 340, contacts 345, or circuit board 360.

Assembly 340 may attach to cable 350 at contacts 345. For example, theinside conductor and braiding of cable 350 may attach to assembly 340 atcontacts 345. Contacts 345 may be located on each side of a portion ofassembly 340. Assembly 340 may be formed using an insulating material,such that an insulative housing is formed. Contacts 345 may connect toconductive leads internal to assembly 340, where the conductive leadscarry power and ground. Assembly 340 may be substantially made ofplastic that is formed around these conductive leads. Assembly 340 mayfurther include a metallic tab 342, which may be coupled to, or anextension of, one of these conductive leads, for example, the conductivelead carrying ground. Metallic tab 342 may be in contact or closeproximity to housing 310. When housing 310 is metallic, this contact orclose proximity can provide an electrical discharge path from housing310 to ground. This can protect cable plug 305 from electrostaticdischarge (ESD), for example, when housing 310 is touched by a user.

Contacts 330 and 332 may fit in passages in assembly 340. Contacts 330may provide power and ground terminals. For example, inside contacts 330may provide a positive power supply while outside contacts 330 mayprovide ground. The passages may be formed at least partly by theconductive leads carrying power and ground, such that power and groundconnections to the pins are formed when contacts 330 are inserted intopassages in assembly 340. Contacts 330 may be pogo pins or other typesof pins. For example, they may be metallic pins inside of a conductivehousing. A spring or other biasing mechanism may be located inside thehousing, such that the pins remain in an extended state until cable plug305 is mated with a compatible connector receptacle. When such matingtakes place, the pins may be pushed back or retracted into housing 310.Contact 332 may be a straight pin that is pushed into a detector circuitwhen cable plug 305 is mated with a compatible connector receptacle,though in other embodiments of the present invention, contact 332 mayalso be a pogo pin or other spring-biased contact.

Front plate 335 may be used to provide an attractive appearance when thecontact portion of cable plug 305 is viewed. Front plate 335 may beplastic or other material and may be formed having a desirable color.For example, the color may match a color of cable 350, housing 310, orother component.

Attraction plate 325 can be magnetically attracted to magnets in acompatible connector receptacle. For example, magnetic field lines mayoriginate in a first magnet in the compatible connector receptacle, passthrough attraction plate 325, and terminate in a second magnet in thecompatible connector receptacle. Attraction plate 325 can be formedusing a ferromagnetic metal or other material. In other embodiments ofthe present invention, attraction plate 325 may be formed using one ormore magnets.

Dust cover 320 may cover attraction plate 325 during transport of thecable assembly or during other times when cable plug 305 is not insertedin a compatible connector receptacle, providing an improved appearanceto cable plug 305. Dust cover 320 may be metal, plastic, ceramic, orother material. For example, dust cover 320 may be formed of atransparent plastic. Dust cover 320 may also reduce or prevent dust orother particulate matter from entering housing 310 through gaps betweenhousing 310 and attraction plate 325. To help users avoid losing dustcover 320, dust cover 320 may be attached to the cable assembly using acord, tie, wire, or other fixture.

Circuit board 360 may fit around assembly 340. Circuit board 360 may bea printed circuit board, flexible circuit board, or other appropriatecircuit board. Circuit board 360 may include detection circuitry thatmay be triggered by contact detect pin 332. Contacts 330 and 332 may besoldered to circuit board 360. Circuit board 360 may be glued orotherwise fixed to assembly 340.

LEDs 365 may be located on circuit board 360. LEDs 365 may light whencontact detect pin 332 is pushed, thereby indicating that cable plug 305has been mated with a compatible connector receptacle.

Light pipes 370 may guide light from LEDs 365. Light pipes 370 may bemade of a transparent material. Light pipes may be colored to giveinteresting or informative coloring to light emitted by LEDs 365. Lightpipes 370 may be fixed to the inside of housing 310.

Light insulators 380 may be used to prevent stray light fromilluminating exits 312. For example, light between plug portion 320 andhousing 310 may otherwise illuminate exit 312, thereby falselyindicating an electrical connection between cable plug 305 and acompatible connector receptacle. Light insulators 380 may be formedusing foam or other opaque material. Light insulators 380 may be fixedto light pipes 370, housing 310, circuit board 360, LEDs 365, or otherappropriate location.

In a specific embodiment of the present invention, during assembly,cable 350 may be inserted through housing 310 such that cable 350emerges from the opening in housing 310 used by contacts 330. Strainrelief 315 and crimping ring 355 may be applied to cable 350. A centerconductor and metallic braiding of cable 350 may be soldered to contacts345. Contacts 330 and 332 may be fit in passages in assembly 340.Circuit board 350, including LEDs 365, may be soldered to contacts 330and 332 and affixed to assembly 340. Front plate 335 and attractionplate 325 may be attached. This assembly may then fit through theopening in housing 310 as cable 350 is pulled away from housing 310. Theextent to which cable 350 is pulled may be determined by a manufacturingfixture. To facilitate the passage of strain relief 315 through housing310, glue may be used. This glue may provide lubrication as strainrelief 315 passes through housing 310. The glue may further act as anadhesive when dry to fix strain relief 315 and cable 350 in placerelative to housing 310. Dust cover 320 may be placed over attractionplate 325 and contacts 330 and 332.

In another embodiment of the present invention, one or more of frontplate 335 and attraction plate 325 are attached after assembly 340 andits connected components are fit through the opening in housing 310.Cable 350 may be inserted through housing 310 such that cable 350emerges from the opening in housing 310 used by contacts 330. Strainrelief 315 and crimping ring 355 may be applied to cable 350. A centerconductor and metallic braiding of cable 350 may be soldered to contacts345. Contacts 330 and 332 may be fit in assembly 340. Circuit board 350,including LEDs 365, may be soldered to contacts 330 and 332 and affixedto assembly 340. Front plate 335 may be attached at this point, or itmay be attached later with attraction plate 325. Alternately, frontplate 335 and attraction plate 325 may be attached at this point, orthey may be attached later. This assembly may then fit through theopening in housing 310 as cable 350 is pulled away from housing 310. Theextent to which cable 350 is pulled may be determined by a manufacturingfixture. To facilitate the passage of strain relief 315 through housing310, glue may be used. This glue may provide lubrication as strainrelief 315 passes through housing 310. The glue may further act as anadhesive when dry to fix strain relief 315 and cable 350 in placerelative to housing 310. Attraction plate 325 and front plate 335 may beattached at this time, as needed. Dust cover 320 may be placed overattraction plate 325 and contacts 330 and 332.

In another embodiment of the present invention, during assembly, thecable and connected components are fit into the end of housing 310.Strain relief 315 and crimping ring 355 may be applied to cable 350. Acenter conductor and metallic braiding of cable 350 may be soldered tocontacts 345. Contacts 330 and 332 may be fit in assembly 340. Circuitboard 350, including LEDs 365, may be soldered to contacts 330 and 332and affixed to assembly 340. Contacts 330 and 332 may be retracted, andassembly 340 and its connected components fit into the end of housing310. Front plate 335 and attraction plate 325 may be attached before orafter insertion. Again, glue may be used as a lubricant when strainrelief 315 is inserted into housing 310. Dust cover 320 may be placedover attraction plate 325 and contacts 330 and 332.

Again, during assembly, light pipes 370 may be fixed to housing 310.Light insulators 380 may be included to reduce the amount of stray lightemitted from exits 312. An example of this structure is shown in thefollowing figure.

FIG. 4 illustrates a side view of a portion of a cable plug 405according to an embodiment of the present invention. Cable plug 405 mayinclude housing 410 having openings or exits 412. Light from LEDs 465may be emitted through exits 412 when cable plug 405 is mated with acompatible connector receptacle (not shown.) Specifically, light fromLED 465 may be guided by LED housing 467 towards light pipe 470. Lightpipe 470 may guide the light through opening or exit 412. Lightinsulators 480 can prevent stray light inside the connector housing 410from being emitted through exit 412. For example, light may seep betweenhousing 410 and attraction plate 420, thereby appearing to falselyindicate that a connection has been made between cable plug 405 and acompatible connector receptacle.

It may be desirable to place a second light pipe in exit 412. If this isdone, it is further desirable that the second light pipe be flush withthe surface of housing 410, such that any ridges or bumps between thesecond light pipe and housing 410 are reduced or eliminated.

Accordingly, in a specific embodiment of the present invention, anadhesive is used to form a second light pipe in exit 412 of housing 410.The adhesive may be placed in exit 412. This adhesive may be lightcuring. Light may be applied to the inside of housing 410 to cure theadhesive. An air flow may be similarly applied to the inside of housing410, thereby pushing the adhesive out exit 412 as it is cured. Excessadhesive can then be wiped from the outside of housing 410, such thatthe surface of the adhesive is flush with the outside of housing 410.Light pipes 470 may be attached to these second light pipes formed bythe adhesive.

Again, it is desirable to use halogen-free materials in manufacturingthe cabling used in these power cable assemblies. Halogen is commonlyused since it provides a flexible cable that is fire-resistant.Unfortunately, materials that are used for halogen-free cabling arethemselves not fire retardant. Further, the addition of fire-retardantchemicals makes halogen-free cables brittle and is therefore notsuitable. Accordingly, various embodiments of the present inventionprovide a strain relief that provides fire protection and ishalogen-free. An example is shown in the following figure.

FIG. 5 illustrates portions of a strain relief 500 according to anembodiment of the present invention. Strain relief 500 includes interiorportion 510 and exterior portion 520. Cabling 516 passes throughinterior portion 510. Interior portion 510 can be formed or molded of asingle piece of material. This material may be a hard plastic, such as apolycarbonate, polycarbonate ABS blend, or other appropriate material.This may provide fire protection, protecting an electronic device thatis being charged.

Outer portion 520 of strain relief 500 may be formed in an additionalmolding step. This type of molding may be referred to as a double-shotprocess. Cable 526 passes through exterior portion 520. Exterior portion520 may be formed around a projection or key 512 of interior portion510, to provide a secure fit between interior portion 510 and exteriorportion 520. Key 512 may have protrusions such that exterior portion 520does not rotate relative to interior portion 510. Exterior portion 520may be made of a flexible material, such as a thermoplastic elastomer,fluorinated ethylene propylene, or other appropriate material. Exteriorportion 520 may provide the flexibility needed to protect cable 526 fromexcessive wear at its interface with strain relief 500 and the housing.

Interior portion 520 may be located in a housing. This housing mayenclose a power transformer or converter, wired or wireless data orcommunication circuitry, or other types of electronics circuitry. Thecolor of exterior portion 520 may be made to match a color of thehousing or cable.

In other embodiments of the present invention, strain relief 500 may beformed using a three step process. In these embodiments, the additionalstep is a first molding step where cables 526 and 516 are covered. Thefollowing two steps provide the remainder of interior portion 510 andexterior portion 520. In various embodiments of the present invention,cables 526 and 516 may be one cable or they may be multiple cables.

FIG. 6 illustrates a strain relief 600 according to an embodiment of thepresent invention. Strain relief 600 includes interior portion 610 andexterior portion 620. Interior portion 610 may provide fire protection,while exterior portion 620 may provide a flexible strain relief A sideof a housing, shown here by dashed lines, may fit in the gap or slot628. Again, the housing may house transformers, data communicationscircuitry, and other types of electronic circuitry.

The above description of embodiments of the invention has been presentedfor the purposes of illustration and description. It is not intended tobe exhaustive or to limit the invention to the precise form described,and many modifications and variations are possible in light of theteaching above. The embodiments were chosen and described in order tobest explain the principles of the invention and its practicalapplications to thereby enable others skilled in the art to best utilizethe invention in various embodiments and with various modifications asare suited to the particular use contemplated. Thus, it will beappreciated that the invention is intended to cover all modificationsand equivalents within the scope of the following claims.

What is claimed is:
 1. A power cable assembly comprising: a cable plugcomprising a unitary housing; a cable attached to the cable plug andhaving a halogen-free jacket; and a strain relief attached to the cableand having a first fire-resistant portion.
 2. The power cable assemblyof claim 1 wherein the unitary housing is formed using aluminum.
 3. Thepower cable assembly of claim 1 wherein the unitary housing issubstantially cylindrical.
 4. The power cable assembly of claim 1wherein the cable plug further comprises an attraction plate.
 5. Thepower cable assembly of claim 4 wherein when the cable plug is insertedin a compatible connector receptacle, magnetic field lines originate ina first magnet in the connector receptacle, pass through the attractionplate, and terminate in a second magnet in the connector receptacle. 6.The power cable assembly of claim 1 wherein the cable jacket is formedusing a thermoplastic elastomer.
 7. The power cable assembly of claim 1wherein the first fire-resistant portion of the strain relief has afire-resistance rating of Vo.
 8. The power cable assembly of claim 7wherein the first fire-resistant portion of the strain relief is formedusing a polycarbonate.
 9. A cable plug comprising: a strain relief thatallows passage of a cable; an assembly comprising a nonconductiveinsulative housing and power and ground conductors, the conductorsterminating in a first and second contact, the first contact coupled toa center conductor of the cable and the second contact coupled to abraiding of the cable, the assembly further comprising passages, thepassages connected to the conductors; a plurality of contact pinslocated in passages in the assembly and having a contact portionextending beyond the assembly such that contact may be made withopposing contacts in a compatible connector receptacle; a circuit boardfixed to the assembly and contact pins; a light emitting diode fixed tothe circuit board; an attraction plate around the contact portion of thecontact pins; and a housing enclosing the assembly, circuit board, andlight emitting diode.
 10. The cable plug of claim 9 wherein the housingis unitary.
 11. The cable plug of claim 9 wherein the assembly furthercomprises a metal tab formed from an end of the ground conductor. 12.The cable plug of claim 9 wherein the contact pins comprise pogo pins.13. The cable plug of claim 9 wherein the contact pins comprise a centerpin, two ground contact pins, and two power supply contact pins.
 14. Thecable plug of claim 13 wherein the power supply contact pins are on eachside of the center pin, and the ground contact pins are on each side ofthe power supply pins away from the center pin.
 15. The cable plug ofclaim 9 further comprising a dust cover over the attraction plate. 16.The cable plug of claim 15 further comprising a front plate between theassembly and a front portion of the cable plug.
 17. The cable plug ofclaim 9 further comprising exit holes in the housing, wherein the exitholes are filled with an adhesive.
 18. A strain relief comprising: afirst molded portion having a first projection and comprising a rigidmaterial having a high fire rating; and a second molded portion moldedaround the first projection and comprising a flexible material.
 19. Thestrain relief of claim 18 wherein the first molded portion is formedusing a polycarbonate, and the second molded portion is formed using athermoplastic elastomer.
 20. The strain relief of claim 18 wherein thefirst molded portion has a fire rating of Vo and the second moldedportion has a fire rating of Hb.